U.S. patent number 8,014,873 [Application Number 12/098,007] was granted by the patent office on 2011-09-06 for apparatus for implanting an electrical stimulation lead.
This patent grant is currently assigned to Advanced Neuromodulation Systems, Inc.. Invention is credited to Terry Daglow, Peter B. Hegi, Thomas K. Hickman, Timothy S. Jones.
United States Patent |
8,014,873 |
Jones , et al. |
September 6, 2011 |
Apparatus for implanting an electrical stimulation lead
Abstract
In one embodiment, an introducer is provided for implanting an
electrical stimulation lead to enable electrical stimulation of
nerve tissue. The introducer includes an outer sheath and an inner
penetrator. The outer sheath may accommodate insertion of the
electrical stimulation lead and may be inserted into a human body
near the nerve tissue. The inner penetrator is removably housed
within the outer sheath and includes an inner channel configured to
accommodate a guide wire, a tip end having a shape and size
substantially conforming to that of the guide wire, a body region
having a shape and size substantially conforming to that of the
outer sheath, and one or more transition regions substantially
connecting the tip end with the body region. At least a portion of
the transition regions of the inner penetrator may flex to
substantially follow flexures in the guide wire during advancement
of the inner penetrator.
Inventors: |
Jones; Timothy S. (Carrollton,
TX), Daglow; Terry (Allen, TX), Hegi; Peter B.
(Dallas, TX), Hickman; Thomas K. (Plano, TX) |
Assignee: |
Advanced Neuromodulation Systems,
Inc. (Plano, TX)
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Family
ID: |
37308564 |
Appl.
No.: |
12/098,007 |
Filed: |
April 4, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080188916 A1 |
Aug 7, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11119438 |
Apr 29, 2005 |
7359755 |
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10637342 |
Aug 8, 2003 |
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Current U.S.
Class: |
607/117; 607/116;
604/164.1; 607/115; 607/118; 604/171; 604/164.01 |
Current CPC
Class: |
A61B
17/3415 (20130101); A61N 1/0553 (20130101); A61B
17/3468 (20130101); A61N 1/36071 (20130101); A61N
1/36021 (20130101); A61N 1/36017 (20130101); A61B
17/3401 (20130101) |
Current International
Class: |
A61N
1/04 (20060101) |
Field of
Search: |
;607/115-118
;604/164,164.1,171 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0972538 |
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Jan 2000 |
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EP |
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03013650 |
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Feb 2003 |
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WO |
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Primary Examiner: Patel; Niketa
Assistant Examiner: Holmes; Rex R
Attorney, Agent or Firm: Hoersten; Craig Crawford;
Christopher S. L. Acosta; Melissa
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No.
11/119,438, filed Apr. 29, 2005, now Pat. No. 7,359,755, which is a
continuation-in-part of U.S. application Ser. No. 10/637,342 filed
Aug. 8, 2003 (now abandoned), the disclosures of which are fully
incorporated herein by reference.
Claims
What is claimed:
1. An introducer for implanting an electrical stimulation lead to
enable electrical stimulation of nerve tissue, comprising: an outer
sheath to accommodate insertion of the electrical stimulation lead
through the outer sheath, the outer sheath operable to be inserted
into a human body near the nerve tissue, the outer sheath including
at least one ridge positioned at a first end of the outer sheath,
the at least one ridge being at least partially circumferentially
positioned about the first end of the outer sheath, the at least
one ridge for providing an indication to a user that the outer
sheath has contacted a part of the anatomy; and an inner penetrator
removably housed within the outer sheath and comprising (i) an
inner channel configured to accommodate a guide wire, (ii) a tip
end having a cross-sectional shape and size substantially
conforming to a cross-sectional shape and size of the guide wire,
(iii) a body region having a cross-sectional shape and size
substantially conforming to a cross-sectional shape and size of the
outer sheath, and (iv) one or more transition regions substantially
connecting the tip end with the body region; wherein the inner
penetrator is configured to be advanced along the guide wire to a
desired location relative to the nerve tissue and removed from the
outer sheath leaving the outer sheath substantially in position for
insertion of the electrical stimulation lead through the outer
sheath into position proximate the nerve tissue; wherein the one or
more transition regions include a tip transition region extending
from the tip end of the inner penetrator at least a portion of the
distance toward the body region of the inner penetrator, and during
the advancement of the introducer along the guide wire, the tip
transition region flexes to substantially follow flexures in the
guide wire, the tip transition region being formed from a
particular material and having a wall thickness that decreases
toward the tip end of the inner penetrator.
2. The introducer of claim 1, wherein the cross-sectional shape and
size of the tip end of the inner penetrator are significantly
different than the cross-sectional shape and size of the body
region of the inner penetrator.
3. The introducer of claim 1, wherein the outer sheath and the body
region of the inner penetrator have substantially oval or oblong
cross-sections, and the guide wire and the tip end of the inner
penetrator have substantially circular cross-sections.
4. The introducer of claim 1, wherein the outer sheath and inner
penetrator are configured from one or more flexible materials such
that the introducer may flex to navigate around physical structures
in the body.
5. The introducer of claim 1, wherein both the outer sheath and the
inner penetrator are formed from one or more of plastic, silastic,
or a polymeric materials.
6. The introducer of claim 1, wherein the one or more transition
regions include a tip transition region extending from the tip end
of the inner penetrator at least a portion of the distance toward
the body region of the inner penetrator, the tip transition region
being formed from a particular material and having a wall thickness
sufficiently thin such that when the inner penetrator is advanced
along the guide wire, the tip transition region may flex to
substantially follow flexures in the guide wire.
7. The introducer of claim 6, wherein the wall thickness of tip
transition region decreases toward the tip end of the inner
penetrator.
8. An introducer for implanting an electrical stimulation lead into
the epidural space of a patient to enable electrical stimulation of
nerve tissue, comprising: an outer sheath to accommodate insertion
of the electrical stimulation lead through the outer sheath, the
outer sheath adapted for insertion into the epidural space of the
patient, the outer sheath including at least one ridge positioned
at a first end of the outer sheath, the at least one ridge being at
least partially circumferentially positioned about the first end of
the outer sheath, the at least one ridge for providing an
indication to a user that the outer sheath has contacted a part of
the anatomy; and an inner penetrator removably housed within the
outer sheath and comprising (i) an inner channel configured to
accommodate a guide wire, (ii) a tip end having a cross-sectional
shape and size substantially conforming to a cross-sectional shape
and size of the guide wire, (iii) a body region having a
cross-sectional shape and size substantially conforming to a
cross-sectional shape and size of the outer sheath, and (iv) a
plurality of flexing transition regions substantially connecting
the tip end with the body region; wherein at least a portion of the
plurality of transition regions are adapted to flex to
substantially follow flexures in the guide wire during advancement
of the introducer along the guide wire; wherein the outer sheath,
the inner penetrator, and the plurality of transition regions allow
the introducer, during entry within the epidural space, to assume a
shape where a distal first portion of the introducer possesses a
substantially linear shape within the epidural space and a second
portion of the introducer exhibits a curve to allow the introducer
to exit from the patient's body.
9. The introducer of claim 8, wherein the introducer flexes to
navigate around physical structures in the body during advancement
of the introducer along the guide wire.
10. The introducer of claim 8, wherein: the guide wire and the tip
end of the inner penetrator have substantially circular
cross-sections; and the outer sheath and the body region of the
inner penetrator have substantially oval cross-sections.
11. The introducer of claim 8, wherein: the plurality of transition
regions include a tip transition region extending from the tip end
of the inner penetrator at least a portion of the distance toward
the body region of the inner penetrator; and during the advancement
of the introducer along the guide wire, the tip transition region
flexes to substantially follow flexures in the guide wire, the tip
transition region being formed from a particular material and
having a wall thickness that decreases toward the tip end of the
inner penetrator.
12. The introducer of claim 8, wherein the plurality of transition
regions include a tip transition region extending from the tip end
of the inner penetrator at least a portion of the distance toward
the body region of the inner penetrator, the tip transition region
having a substantially circular cross-section extending along the
length of the tip transition region, the substantially circular
cross-section having an inner diameter and an outer diameter, both
the inner diameter and the outer diameter of the substantially
circular cross-section tapering toward the tip end of the tip
transition region.
13. The introducer of claim 8, wherein the plurality of transition
regions include a tip transition region, a body transition region,
and a middle transition connecting the tip transition region with
the body transition region, the tip transition region and the body
transition region being tapered, and the middle transition not
being tapered.
14. An introducer for implanting an electrical stimulation lead to
enable electrical stimulation of nerve tissue, comprising: an outer
sheath to accommodate insertion of the electrical stimulation lead
through the outer sheath, the outer sheath adapted for insertion
into a human body near nerve tissue, the outer sheath including at
least one ridge positioned at a first end of the outer sheath, the
at least one ridge being at least partially circumferentially
positioned about the first end of the outer sheath, the at least
one ridge for providing an indication to a user that the outer
sheath has contacted a part of the anatomy; and an inner penetrator
removably housed within the outer sheath and comprising (i) an
inner channel configured to accommodate a guide wire, (ii) a tip
end having a cross-sectional shape and size substantially
conforming to a cross-sectional shape and size of the guide wire,
(iii) a body region having a cross-sectional shape and size
substantially conforming to a cross-sectional shape and size of the
outer sheath, and (iv) a plurality of flexing transition regions
substantially connecting the tip end with the body region; wherein
the tip end of the inner penetrator comprises (i) a needle nose
segment that possesses an approximately constant outer diameter,
the needle nose segment comprising an aperture for providing an
interference fit with the guide wire and (ii) a transition segment
that transitions from the shape of the needle nose segment to the
shape of the body portion of the inner penetrator.
15. The introducer claim 14 wherein the needle nose segment is more
flexible than the transition segment and the transition segment is
more flexible than the body portion of the inner penetrator.
Description
BACKGROUND
This invention relates generally to electrical stimulation leads
for medical applications and in particular to a method and
apparatus for implanting an electrical stimulation lead using a
flexible introducer One method of delivering electrical energy is
to implant an electrode and position it in a precise location
adjacent the spinal cord such that stimulation of the electrode
causes a subjective sensation of numbness or tingling in the
affected region of the body, known as "paresthesia." Pain managing
electrical energy is commonly delivered through electrodes
positioned external to the dura layer surrounding the spinal cord.
The electrodes may be carried by either of two primary vehicles: a
percutaneous lead and a laminotomy or "paddle" lead.
Percutaneous leads commonly have three or more equally-spaced
electrodes. They are positioned above the dura layer using a needle
that is passed through the skin, between the desired vertebrae and
onto the top of the dura. Percutaneous leads deliver energy
radially in all directions because of the circumferential nature of
the electrode. Percutaneous leads can be implanted using a
minimally invasive technique. In a typical percutaneous lead
placement, a trial stimulation procedure is performed to determine
the optimal location for the lead. Here, a needle is placed through
the skin and between the desired vertebrae. The percutaneous lead
is then threaded through the needle into the desired location over
the spinal cord dura. Percutaneous leads may also be positioned in
other regions of the body near peripheral nerves for the same
purpose.
Laminotomy or paddle style leads have a paddle-like configuration
and typically possess multiple electrodes arranged in one or more
independent columns. Paddle style leads provide a more focused
energy delivery than percutaneous leads because electrodes may be
present on only one surface of the lead. Paddle style leads may be
desirable in certain situations because they provide more direct
stimulation to a specific surface and require less energy to
produce a desired effect. Because paddle style leads are larger
than percutaneous leads, they have historically required surgical
implantation through a procedure known as partial laminectomy that
requires the resection and removal of vertebral tissue.
SUMMARY OF THE INVENTION
The present invention provides an introducer and process for
implanting a paddle style electrical stimulation lead.
In one embodiment, an introducer is provided for implanting a
paddle style electrical stimulation lead to enable electrical
stimulation of nerve tissue. The introducer includes an outer
sheath and an inner penetrator. The outer sheath may accommodate
insertion of the paddle style electrical stimulation lead and may
be inserted into a human body near the nerve tissue. The inner
penetrator is removably housed within the outer sheath and includes
an inner channel configured to accommodate a guide wire, a tip end
having a shape and size substantially conforming to that of the
guide wire, a body region having a shape and size substantially
conforming to that of the outer sheath, and one or more transition
regions substantially connecting the tip end with the body region.
The inner penetrator may be advanced along the guide wire to a
desired location relative to the nerve tissue and removed from the
outer sheath leaving the outer sheath substantially in position for
insertion of the paddle style electrical stimulation lead through
the outer sheath into position proximate the nerve tissue. At least
a portion of the transition regions of the inner penetrator may
flex to substantially follow flexures in the guide wire during
advancement of the inner penetrator along the guide wire.
In another embodiment, a method is provided for implanting a paddle
style electrical stimulation lead to enable electrical stimulation
of nerve tissue. The method includes inserting a needle into
tissue, positioning a guide wire through the needle into a desired
location relative to the nerve tissue, removing the needle, and
forming a tract for the paddle style electrical stimulation lead by
advancing an introducer along the guide wire to a desired location.
The introducer includes an outer sheath and inner penetrator
removably housed within the outer sheath, the inner penetrator
including a tip end having a cross-sectional shape and size
substantially conforming to a cross-sectional shape and size of the
guide wire, a body region having a cross-sectional shape and size
substantially conforming to a cross-sectional shape and size of the
outer sheath, and one or more transition regions substantially
connecting the tip end with the body region. At least a portion of
the one or more transition regions flexes to substantially follow
flexures in the guide wire during advancement of the inner
penetrator along the guide wire. After advancing the introducer
along the guide wire to the desired location, the inner penetrator
is removed, leaving the outer sheath substantially in position, and
the paddle style electrical stimulation lead is inserted through
the outer sheath until the paddle style electrical stimulation lead
is positioned proximate the nerve tissue.
In another embodiment, a method is provided for implanting an
electrical stimulation lead in a minimally invasive percutaneous
manner to enable electrical stimulation of a human's spinal nerve
tissue. The method includes inserting a needle into the human's
epidural space and inserting a guide wire through the needle until
an end of the guide wire is positioned in the epidural space at a
desired location relative to the spinal nerve tissue to be
stimulated. The position of the guide wire in the epidural space is
verified using fluoroscopy, and the needle is removed, leaving the
guide wire substantially in position. An introducer is advanced
along the guide wire until an end of the inner penetrator of the
introducer is positioned in the epidural space at a desired
location with respect to the spinal nerve tissue to be stimulated.
The introducer includes an outer sheath and an inner penetrator
removably housed within the outer sheath, the inner penetrator of
the introducer including an inner channel configured to accommodate
the guide wire, a tip end having a cross-sectional shape and size
substantially conforming to a cross-sectional shape and size of the
guide wire, a body region having a cross-sectional shape and size
substantially conforming to a cross-sectional shape and size of the
outer sheath, and one or more transition regions substantially
connecting the tip end with the body region. as the inner
penetrator of the introducer advances along the guide wire, at
least one of the tip transition regions flexes to substantially
follow flexures in the guide wire, and the outer sheath of the
introducer forms a tract in the epidural space. The position of the
introducer in the epidural space is verified using fluoroscopy. The
guide wire and the inner penetrator of the introducer are removed,
leaving the outer sheath of the introducer substantially in
position. The electrical stimulation lead is inserted through the
outer sheath of the introducer until the electrical stimulation
lead is positioned in the epidural space proximate the spinal nerve
tissue to be stimulated, and the positioning of the paddle style
electrical stimulation lead in the epidural space is verified using
fluoroscopy.
In another embodiment, a system for implanting a paddle style
electrical stimulation lead to enable electrical stimulation of a
human's spinal nerve tissue is provided. The system includes a
needle, a guide wire, and an introducer. The introducer includes an
outer sheath and an inner penetrator. The outer sheath is
configured to accommodate insertion of the paddle style electrical
stimulation lead through the outer sheath and may be inserted
through the human's skin and into the human's epidural space. The
inner penetrator is removably housed within the outer sheath and
includes an inner channel configured to accommodate a guide wire, a
tip end having a cross-sectional shape and size substantially
conforming to a cross-sectional shape and size of the guide wire, a
body region having a cross-sectional shape and size substantially
conforming to a cross-sectional shape and size of the outer sheath,
and one or more transition regions substantially connecting the tip
end with the body region. The inner penetrator may be advanced
along the guide wire until an end of the inner penetrator is
positioned in the epidural space at a desired location relative Lo
spinal nerve tissue to be stimulated, the outer sheath forming an
insertion tract as the inner penetrator advances along the guide
wire. A tip transition region of the inner penetrator is formed
from a particular material and has a wall thickness sufficiently
thin such that during advancement of the inner penetrator along the
guide wire, the tip transition region may flex to substantially
follow flexures in the guide wire. The inner penetrator is
configured to be removed from the outer sheath leaving the outer
sheath substantially in position for insertion of the paddle style
electrical stimulation lead through the outer sheath into position
proximate the spinal nerve tissue to be stimulated. The system also
includes an implantable generator to power the paddle style
electrical stimulation lead.
In another embodiment, a lead introducer kit for preparing to
implant an electrical stimulation lead for electrical stimulation
of nerve tissue is provided. The lead introducer kit includes a
needle, a guide wire, a lead blank having a similar shape and size
as an electrical stimulation lead to be inserted proximate the
nerve tissue, and an introducer. The lead blank is configured for
insertion into the human body to determine whether the electrical
stimulation lead may be inserted into position proximate nerve
tissue to be stimulated. The introducer includes an outer sheath
and an inner penetrator. The outer sheath is operable to be
inserted into a human body near nerve tissue to be stimulated. The
inner penetrator is removably housed within the outer sheath and
includes an inner channel configured to accommodate the guide wire.
The inner penetrator is configured to be advanced along the guide
wire to a desired location relative to the nerve tissue and removed
from the outer sheath leaving the outer sheath substantially in
position for insertion of the lead blank through the outer sheath
to determine whether the electrical stimulation lead may be
inserted into position proximate the nerve tissue to be
stimulated.
In another embodiment, a method of removing an electrical
stimulation lead from a human body is provided. A stimulation lead
introducer is positioned over a body portion of an electrical
stimulation lead that is at least partially implanted in a human
body. The stimulation lead introducer includes an outer sheath and
an inner penetrator removably housed within the outer sheath and
comprising an inner channel, a tip region of the inner penetrator
extending out from the outer sheath, the stimulation lead
introducer being positioned such that the body portion of the
electrical stimulation lead is partially disposed within an inner
channel of the inner penetrator. The stimulation lead introducer is
advanced along the body portion of the electrical stimulation lead
until the tip region of the inner penetrator is located adjacent a
stimulation portion of the electrical stimulation lead. The outer
sheath is advanced relative to the inner penetrator until the outer
sheath covers at least a portion of the stimulation portion of the
electrical stimulation lead. The outer sheath, the inner
penetrator, and the electrical stimulation lead are then removed
from the human body.
Particular embodiments of the present invention may provide one or
more technical advantages. For example, certain embodiments may
allow a paddle style electrical stimulation lead to be inserted
using a minimally invasive procedure, using an introducer, rather
than a partial laminectomy or other more invasive surgical
procedure. Certain embodiments may provide a guide wire, introducer
and paddle style electrical stimulation lead composed in part or
entirely of radio-opaque material to allow for fluoroscopic
verification of the position of the guide wire, introducer and
lead. Certain embodiments may provide an inner penetrator including
a hollow tip configured to extend beyond the outer sheath, the tip
having a raised circumferential ridge configured to create
resistance when the circumferential ridge contacts the human's
tissue. Other embodiments may provide a smooth transition between
the inner penetrator and the outer sheath to prevent the introducer
from getting caught or stuck in the tissue. Certain embodiments may
provide an inner penetrator having a substantially flexible tip
that may flex to maneuver around obstructions or physical
structures in the body and/or to follow curvatures in a guide wire.
Certain embodiments may provide a lead introducer kit including a
lead blank that may be used to determine whether an actual
electrical stimulation lead may be inserted into a desired position
in the body. Thus, in situations where it is determined (using the
lead blank) that the actual lead cannot be inserted into the
desired position in the body, the actual lead not need to be
removed from its packaging or inserted into the body, thus saving
the actual lead for another use. Certain embodiments may provide a
desirable method for removing an implanted electrical stimulation
lead using a lead introducer having an outer sheath and in inner
penetrator. Certain embodiments may provide all, some, or none of
these advantages. Certain embodiments may provide one or more other
technical advantages, one or more of which may be readily apparent
to those skilled in the art from the figures, description and
claims included herein.
BRIEF DESCRIPTION OF THE DRAWINGS
To provide a more complete understanding of the present invention
and the features and advantages thereof, reference is made to the
following description taken in conjunction with the accompanying
drawings, in which:
FIG. 1A illustrates an example introducer for implanting a paddle
style electrical stimulation lead according to one embodiment of
the invention;
FIG. 1B illustrates an example inner penetrator of the introducer
shown in FIG. 1A;
FIG. 1C illustrates an example of an outer sheath of the introducer
shown in FIG. 1A;
FIG. 1D illustrates an example of a tip of the introducer shown in
FIG. 1A;
FIG. 1E illustrates an example of a tip of the outer sheath of the
introducer shown in FIG. 1A;
FIG. 1F illustrates a side view of an example of the tip of the
introducer shown in FIG. 1A;
FIG. 2A illustrates an example introducer for implanting a paddle
style electrical stimulation lead according to another embodiment
of the invention;
FIG. 2B illustrates an example inner penetrator of the introducer
shown in FIG. 2A;
FIG. 2C illustrates an example of an outer sheath of the introducer
shown in FIG. 2A;
FIG. 2D illustrates a perspective view of the introducer shown in
FIG. 2A;
FIG. 2E illustrates an example tip region of the inner penetrator
shown in FIG. 2B;
FIGS. 2F-2H illustrate an example of a body portion and tip portion
of the outer sheath shown in FIG. 2C;
FIG. 3A illustrates an example of a needle inserted into a human's
epidural space;
FIG. 3B illustrates an example of a guide wire being inserted
through a needle into a human's epidural space;
FIG. 3C illustrates an example of an introducer being inserted over
a guide wire into a human's epidural space;
FIG. 3D illustrates an example of an inner penetrator being removed
from the outer sheath of an introducer in a human's epidural
space;
FIG. 3E illustrates an example of a paddle style lead being
inserted through an introducer into a human's epidural space;
FIG. 3F illustrates an example of a paddle style lead implanted in
a human's epidural space;
FIG. 4A illustrates an example of a stimulation system;
FIG. 4B illustrates an example of a stimulation system; and
FIG. 5 is a flow chart describing steps for implanting a
stimulation system;
FIGS. 6A-6E illustrate an example method of removing an implanted
paddle style electrical stimulation lead from a human's epidural
space using an introducer according to one embodiment of the
invention;
FIGS. 7A-7D illustrate example views of a lead introducer flexing
as it moves along a guide wire within the body according to certain
embodiments of the invention;
FIG. 8 illustrates an example lead introducer kit for preparing to
implant an electrical stimulation lead for electrical stimulation
of nerve tissue in a human, according to one embodiment of the
invention;
FIG. 9 illustrates an example lead blank including a paddle style
stimulating portion having a scalloped shape;
FIG. 10 illustrates an example paddle style electrical stimulation
lead having electrodes on only one side, and markings indicating
the directional orientation of the lead, according to one
embodiment of the invention;
FIG. 11 illustrates an example paddle style electrical stimulation
lead having a substantially uniform paddle-shaped cross-section
extending along the body of the lead, according to one embodiment
of the invention; and
FIG. 12 illustrates an example paddle style electrical stimulation
lead having a tear away body portion, according to one embodiment
of the invention.
DESCRIPTION OF EXAMPLE EMBODIMENTS
FIG. 1A illustrates an example introducer 10a for implanting a
paddle style electrical stimulation lead percutaneously according
to one embodiment of the invention. Introducer 10a may be used to
percutaneously introduce a percutaneous or paddle style lead into
the epidural space of a user who requires electrical stimulation
treatment directed to spinal nerve tissue, for example, for pain
management. For example, and not by way of limitation, introducer
10a may be used to percutaneously introduce any of the percutaneous
or paddle style leads shown and/or described in U.S. Publication
No. 2002/0022873, filed on Aug. 10, 2001; U.S. Provisional
Application No. 60/645,405, filed on Apr. 28, 2004; and/or U.S.
Provisional Application No. 60/566,373, filed on Jan. 19, 2005. The
same or an analogous, perhaps smaller, introducer 10a may be used
to implant a percutaneous or paddle style lead into other tissue
for electrostimulation treatment of a peripheral nerve. In one
embodiment, introducer 10a includes an outer sheath 12a and an
inner penetrator 14a.
FIG. 1B illustrates an example inner penetrator 14a disassembled
from outer sheath 12a. Inner penetrator 14a includes handle 16a,
connector 17a, and body 18a having proximal end 19a and distal end
or tip 20a. Tip 20a may be tapered. Connector 17a connects handle
16a to body 18a. An inner channel 22a is formed through handle 16a
and body 18a and connects opening 26a of handle 16a to opening 21a
of tip 20a. Inner channel 22a may be configured to attach to a
syringe. Inner channel 22a is wide enough to accommodate guide
wires of various sizes along which introducer 10a may be advanced
during use. Channel 22a may taper or otherwise decrease in diameter
as it traverses connector 17a at the handle-body junction. Inner
penetrator 14a may be formed from a plastic, such as silastic, HDPE
or another polymer, or any other suitable material. Tip 20a of
inner penetrator 14a may be curved as shown in FIGS. 1A-1C or may
be curved into any other suitable shapes by an operator before
inserting the introducer. In certain embodiments, inner penetrator
14a may be bent or curved into a suitable configuration to allow
passage around an anatomical obstruction, or formed into any other
shape suitable for particular anatomic regions of the body.
FIG. 1C illustrates outer sheath 12a disassembled from inner
penetrator 14a. The lumen 28 of outer sheath 12a may range in
width, for example from approximately 2 mm to approximately 6 mm.
Lumen 28 may be oblong, oval, or substantially rectangular as
needed to accommodate paddle style leads of various configurations.
Outer sheath 12a may taper slightly at tip 29. Tip 29 of outer
sheath 12a may be beveled to allow easier passage through tissue
and to allow inner penetrator 14a to protrude out of tip 29.
In some embodiments, outer sheath 12a may be formed from a flexible
material, such as a plastic or polymer, such as PEBAX, or any other
suitable polyethylene type material, for example, such that outer
sheath 12a may flex to follow a guide wire and/or to maneuver
around obstructions or physical structures in the body. In other
embodiments, outer sheath 12a may be formed from a more rigid
material, such as a metal, such as stainless steel or titanium, or
any other suitable material that is stiff and resists bending when
outer sheath 12a is inserted through the paravertebral tissue and
into the epidural space. In one embodiment, inner penetrator 14a
includes tapered tip 20a shown in FIG. 1D. Tapered tip 20a
protrudes out of outer sheath 12a. Tapered tip 20a preferably
allows introducer 10a to pass easily over a guide wire without
creating a false passage in an undesirable location in the
tissue.
In one embodiment of outer sheath 12a, shown in FIGS. 1D-1F, tip
20a includes a raised circumferential shoulder or ridge 23a
configured to provide an indication or "feel" to a physician as
raised ridge 23a comes in contact with the ligamentum flavum. This
"feel" occurs when raised ridge 23a comes in contact with the
ligamentum flavum causing a slight resistance, pressure, or "notch"
feel to the physician as raised ridge 23a comes in contact with and
passes through the ligamentum flavum. As many physicians rely on
"feel" while performing delicate procedures, this aspect may
provide an important indication to the physician as to the location
of outer sheath 12a and thus introducer 10a as a whole.
Such a raised ridge 23a can also be applied to needles or cutting
devices that otherwise fail to provide physicians sufficient "feel"
or a locative indication as the needle cuts through the ligamentum
flavum. For example, the edge of outer sheath 12a in FIG. 1E could
be configured into a cutting surface for a paddle insertion type
needle. The improvement of raised ridge 23a on such a cutting
device would provide the needed "feel" or indication to the
physician as to where the needle was in the human tissue, thus
providing confidence to the physician, as the physician uses such a
large needle, that the needle has not yet entered the interthecal
space.
Further, raised ridge 23a assists in spreading the fibers of the
paravertebral muscle and ligaments as it is inserted. Raised ridge
23a may be angled to assist insertion, for example, at an angle of
thirty-five to forty-five degrees or any other angle that would
facilitate passage of outer sheath through tissue. During
insertion, raised ridge 23a ultimately makes contact with the
ligamentum flavum and rests against it during insertion of a guide
wire and an electrical stimulation lead.
As shown in FIGS. 1D and 1E, in some embodiments, outer sheath 12a,
lumen 28a, and inner penetrator 14a may have oblong, oval, or
substantially rectangular cross-sections as needed to accommodate
paddle style leads of various configurations. Such configuration
also prevents inner penetrator 14a from rotating within lumen 28a
of outer sheath 12a, which may be advantageous for inserting a lead
into the target region in the body. For example, such configuration
that prevents the rotation of inner penetrator 14a within lumen 28a
may allow an operator to ensure that the lead is facing in the
desired direction. In addition, a non-circular cross-section may
provide additional flexibility to introducer 10, which may be
advantageous for navigating into particular regions in the body,
such as the epidural region, for example.
In one embodiment, outer sheath 12a, inner penetrator 14a, or both
may be formed from radio-opaque material or may include
radio-opaque markers that allow the position of outer sheath 12a,
inner penetrator 14a, or both to be visualized with fluoroscopy or
plain x-rays, for example, during the insertion process to insure
proper positioning in the epidural space.
FIG. 2A illustrates another example introducer 10b for implanting a
paddle style electrical stimulation lead percutaneously according
to another embodiment of the invention. Introducer 10b may be used
to percutaneously introduce a percutaneous or paddle style lead
into the epidural space of a user who requires electrical
stimulation treatment directed to nerve tissue (e.g., spinal nerve
tissue), for example, for pain management. The same or an
analogous, perhaps smaller, introducer 10b may be used to implant a
percutaneous or paddle style lead into other tissue for
electrostimulation treatment of a peripheral nerve. Like introducer
10a, introducer 10b may include an outer sheath 12b and an inner
penetrator 14b.
FIG. 2B illustrates an example inner penetrator 14b disassembled
from outer sheath 12b. Inner penetrator 14b includes a handle
portion 16b, a body portion 18b, a distal or tip end 20b, and a tip
portion 25b connecting body portion 18b with a tip end 20b. Tip
portion 25b may include one or more transition regions 26b, which
may provide a transition between the cross-sectional shape and size
of body portion 18b and the cross-sectional shape and size of tip
end 20b, as discussed in greater detail with reference to FIG. 2D.
For example, one or more transition regions 26b may be tapered.
Handle portion 16b may include an inner penetrator locking device
32b, which may interact with a locking device of outer sheath 12b
(discussed below regarding FIG. 2C) in order to lock inner
penetrator 14b in position within outer sheath 12b. However, any
other type of handle known to those in the art may also be
used.
An inner channel 22b is formed through handle portion 16b, body
portion 18b, and tip portion 25b to connect an opening 26b in
handle portion 16b with an opening 21b in tip end 20b. Inner
channel 22b may be configured to attach to a syringe at a lure lock
located at handle portion 16b or through another opening. Inner
channel 22b may be configured to accommodate guide wires of various
sizes along which introducer 10b may be advanced during use. In
this embodiment, the diameter of inner channel 22b tapers proximate
handle portion 16b, remains constant along the length of body
portion 16b, and tapers slightly proximate tip region 25b. However,
in other embodiments, inner channel 22b may not include a tapered
portion. Inner penetrator 14b may be formed from a plastic, such as
silastic, HDPE or another polymer, or any other suitable material.
In addition, in some embodiments, the shape of inner penetrator 14b
may be configured to facilitate steering of inner penetrator 14b.
For example, one or more indentions, notches, or score lines may be
formed in inner penetrator 14b to increase the flexibility and
steerability of inner penetrator 14b.
FIG. 2C illustrates outer sheath 12b disassembled from inner
penetrator 14b. Outer sheath 12b includes a handle portion 27b, a
body portion 31b, a tip portion 30b, and a tip end 29b through
which inner penetrator 14b may protrude, such as shown in FIGS. 2A
and 2D. The inner channel, or lumen, 28b of outer sheath 12b may
range in width, for example from approximately 2 mm to
approximately 6 mm. In some embodiments, the cross-section of lumen
28b may be oblong, oval, or substantially rectangular as needed to
accommodate paddle style leads of various configurations. The outer
surface of outer sheath 12b may have a similar cross-section as
lumen 28b. Thus, for example, the outer surface of outer sheath 12b
may have an oblong, oval, or substantially rectangular
cross-section. In some embodiments, outer sheath 12b, lumen 28b,
and inner penetrator 14b may have oblong, oval, or substantially
rectangular cross-sections as needed to accommodate paddle style
leads of various configurations. As discussed above regarding
introducer 10a, such configuration may prevent inner penetrator 14b
from rotating within lumen 28b of outer sheath 12b, which may be
advantageous for inserting and/or navigating a lead into the target
region in the body. Outer sheath 12b may taper slightly proximate
tip end 29b, which may be beveled to be substantially flush against
the outer surface of inner penetrator 14b to allow easier passage
through tissue, as discussed below.
In some embodiments, outer sheath 12b is formed from a plastic or
polymer material, or any other suitable material that allows
flexing when outer sheath 12b is inserted through certain tissue,
such as the paravertebral tissue and into the epidural space, for
example. In a particular embodiment, both outer sheath 12b and
inner penetrator 14b are formed from plastic or polymer materials,
but inner penetrator 14b is more flexible than outer sheath 12b due
to the particular materials used to form outer sheath 12b and inner
penetrator 14b and/or the size, wall thickness, or other dimensions
of outer sheath 12b and inner penetrator 14b. In other embodiments,
outer sheath 12b is formed from substantially rigid material, such
as a metal, such as stainless steel or titanium, or any other
suitable material that is stiff and resists flexing when outer
sheath 12b is inserted through the paravertebral tissue and into
the epidural space.
Handle portion 27b may include an outer sheath locking device 33b,
which may interact with inner penetrator locking device 32b shown
in FIG. 2B in order to lock inner penetrator 14b in position within
outer sheath 12b. Inner penetrator locking device 32b and outer
sheath locking device 33b may include any devices suitable to
interact to lock inner penetrator 14b within outer sheath 12b. For
example, locking devices 32b and 33b may include threaded portions
such that inner penetrator 14b and outer sheath 12b may be locked
and unlocked by rotation of at least one of locking devices 32b and
33b. As another example, locking devices 32b and 33b may snap
together to lock inner penetrator 14b within outer sheath 12b.
Locking inner penetrator 14b within outer sheath 12b may prevent
outer sheath 12b from sliding down over inner penetrator 14b, which
may damage tissue in the body or cause other problems. However,
some embodiments do not include a locking mechanism.
In some embodiments, inner penetrator 14b and/or outer sheath 12b
may be partially or completely formed from one or more materials
that may be detected by one or more medical imaging techniques,
such as ultrasound, fluoroscopy, MRI, fMRI and/or X-ray, such that
the location of the inner penetrator 14b and/or outer sheath 12b
within the human body may be determined. For example, inner
penetrator 14b and/or outer sheath 12b may be formed from or doped
with a radio-opaque material, such as barium sulphate (BaSO.sub.4),
for example. As another example, inner penetrator 14b and/or outer
sheath 12b may include markers that may be detected by one or more
of such medical imaging techniques. As shown in FIGS. 2B and 2C,
inner penetrator 14b may include a first radio-opaque marker 34b
and outer sheath 12b may include a second radio-opaque marker 35b.
The location of inner penetrator 14b relative to outer sheath 12b
may be determined based on the determined relative location of
markers 34b and 35b. In addition, first and second radio-opaque
markers 34b and 35b may have different radiopacity such that
markers 34b and 35b may be distinguished from each other.
FIG. 2D illustrates a perspective view of introducer 10b. In this
configuration, inner penetrator 14b may be locked within outer
sheath 12b by locking devices 32b and 33b. Tip portion 25b of inner
penetrator 14b protrudes through tip end 29b of outer sheath 12b.
As discussed below with reference to FIGS. 3A-3F, inner penetrator
14b may be configured to be advanced along a guide wire to a
desired location relative to particular nerve tissue to be
stimulated and removed from outer sheath 12b, leaving outer sheath
12b substantially in position for insertion of an electrical
stimulation lead through outer sheath 12b into position proximate
the nerve tissue to be stimulated. Tip portion 25b of inner
penetrator 14b may be sufficient to flex to substantially follow
flexures (such as bends or curves) in the guide wire during
advancement of inner penetrator 14b along the guide wire. In order
to provide such flexibility, tip portion 25b may be formed from
particular flexible materials and may have sufficiently thin walls,
as discussed below with reference to FIG. 2E. In addition, as
discussed above, outer sheath 12b may be formed from flexible
materials and may have sufficiently thin walls in order to provide
some flexibility of introducer 10b.
FIG. 2E illustrates a partial detailed view of body portion 18b and
tip portion 25b of inner penetrator 14b, as well as a portion of
tip portion 30b of outer sheath 12b, of introducer 10b. In this
embodiment, tip portion 25b of inner penetrator 14b includes three
transition regions 26b, which may provide a transition between the
cross-sectional shape and size of body portion 18b and the
cross-sectional shape and size of tip end 20b. Transition regions
26b include a tip transition region 36b, a middle transition region
37b, and a body transition region 38b. Tip transition region 36b
has a substantially circular cross-section extending along the
length of tip transition region 36b and tapering slightly toward
tip end 20b. Middle transition region 37b has a substantially
circular and constant cross-section along the length of middle
transition region 37b. Thus, in this embodiment, middle transition
region 37b is not tapered. Body transition region 38b has a
cross-section that transitions from the cross-section of body
portion 18b, which may substantially match the cross-section of
lumen 28b of outer sheath 12b. In a particular embodiment, body
transition region 38b transitions from a substantially oval
cross-section adjacent body portion 18b to a substantially circular
cross-section adjacent middle transition region 37b. Body
transition region 38b may have a more severe taper than tip
transition region 36b.
The materials and dimensions of one or more of tip transition
region 36b, middle transition region 37b, and body transition
region 38b may be selected to provide substantial flexibility to
tip region 25b such that inner penetrator 14b may flex around
particular features in the body, and such that when the inner
penetrator 14b is advanced along a guide wire, tip regions 25b may
flex to substantially follow flexures in the guide wire such that
the guide wire is not significantly displaced by the advancing tip
region 25b of inner penetrator 14b.
For example, the wall thickness of tip transition region 36b,
denoted as thickness "T.sub.ipt," may decrease toward tip end 20b.
In some embodiments, the wall thickness T.sub.ipt of tip transition
region 36b is less than or approximately equal to 0.02 inches at
its thickest point along tip transition region 36b. The wall
thickness T.sub.ipt of tip transition region 36b may be less than
0.01 inches at tip end 20b. In a particular embodiment, the wall
thickness T.sub.ipt is approximately 0.006 inches at tip end 20b.
The decreased wall thickness, T.sub.ipt, of tip transition region
36b toward tip end 20b may provide for increased flexibility of tip
transition region 36b. In addition, as shown in FIG. 2E, both the
inner diameter, denoted as "ID.sub.ipt," and the outer diameter,
denoted as "OD.sub.ipt," of tip transition region 36b may decrease
or taper toward tip end 20b. The tapered outer diameter OD.sub.ipt
and reduced wall thickness, T.sub.ipt, of tip transition region 36b
at tip end 20b may provide a relatively smooth transition between
tip end 20b and a guide wire extending through tip opening 21b.
Such smooth transition may reduce or eliminate the likelihood of
the juncture between tip end 20b and a guide wire getting stuck or
caught up, or pushing tissue forward, as inner penetrator 14b is
advanced within the body.
The tapered inner diameter ID.sub.ipt may provide for a tight or
close fit at tip end 20b with a guide wire running through opening
22b of inner penetrator 14b. In some embodiments, the tapered inner
diameter ID.sub.ipt provides for an interference fit between inner
penetrator 14b and a guide wire, at least at tip end 20b of inner
penetrator 14b.
In addition, the length of tip transition region 36b, denoted as
length "L.sub.ipt," compared to wall thickness T.sub.ipt, inner
diameter ID and/or outer diameter OD, may be selected to provide
desired flexibility of tip transition region 36b. For example, the
ratio of the length L.sub.ipt to wall thickness T.sub.ipt at the
thickest point may be greater than or approximately equal to 20 to
1. As another example, the ratio of the length L.sub.ipt to outer
diameter OD.sub.ipt may be greater than or approximately equal to
2.5 to 1. Such configuration and dimensions may provide desired
flexibility for tip transition region 36b.
The wall thickness of middle transition region 37b, denoted as
thickness "T.sub.ipm," which remains substantially constant along
the length of middle transition region 37b, may be less than or
approximately equal to 0.02 inches. In a particular embodiment,
wall thickness T.sub.ipm is approximately 0.010 inches. Such
configuration and dimensions may provide desired flexibility for
middle transition region 37b.
In addition, the length of middle transition region 37b, denoted as
length "L.sub.ipm," compared to wall thickness T.sub.ipm, the inner
diameter and/or the outer diameter of middle transition region 37b,
may be selected to provide desired flexibility of middle transition
region 36b. For example, the ratio of the length L.sub.ipm to wall
thickness T.sub.ipm may be greater than or approximately equal to
30 to 1. As another example, the ratio of the length L.sub.ipm to
the outer diameter of middle transition region 37b may be greater
than or approximately equal to 3 to 1. Such configuration and
dimensions may provide desired flexibility for middle transition
region 37b.
The total length of tip transition region 36b and middle transition
region 37b (L.sub.ipt+L.sub.ipm) compared to the wall thickness at
the thickest point along transition regions 36b and 37b or compared
to the inner diameter and/or the outer diameter of middle
transition region 37b, may be selected to provide desired
flexibility of middle transition region 36b. For example, the ratio
of the total length of tip transition region 36b and middle
transition region 37b (L.sub.ipt+L.sub.ipm) to the wall thickness
T.sub.ipm may be greater than or approximately equal to 40 to 1. As
another example, the ratio of the total length of tip transition
region 36b and middle transition region 37b (L.sub.ipt+L.sub.ipm)
to the outer diameter of middle transition region 37b may be
greater than or approximately equal to 5 to 1. Such configuration
and dimensions may provide desired flexibility for tip portion 25b
of inner penetrator 14b. The relatively long nose provided by tip
transition region 36b and middle transition region 37b may provide
more flexibility than a tip having a substantially uniform taper
from body portion 18b to the tip end 20b of inner penetrator 14b,
which flexibility may be desirable for navigating inner penetrator
14b along a guide wire, for example.
Although the embodiment shown in FIG. 2E includes three transition
regions 26b, it should be understood that other embodiments may
include more or less than three transition regions 26b (which may
or may not include one or more transition regions 26b similar to
transition regions 36b, 37b and/or 38b shown in FIG. 2E), or zero
transition regions 26b.
In the embodiment shown in FIG. 2E, when inner penetrator 14b is
fully advanced within (and/or locked together with) outer sheath
12b, a portion of the body portion 18b of inner penetrator 14b may
protrude out through tip end 29b of outer sheath 12b. As discussed
below, tip portion 30b of outer sheath 12b may be tapered to
provide a relatively smooth transition between tip end 29b and body
portion 18b of inner penetrator 14b protruding through tip end 29b.
In other embodiments, body portion 18b of inner penetrator 14b may
not protrude through tip end 29b of outer sheath 12b when inner
penetrator 14b is fully advanced within (and/or locked together
with) outer sheath 12b. In one embodiment, tip end 29b may
substantially align with the intersection of body portion 18b and
body transition region 38b of inner penetrator 14b.
FIGS. 2F-2H illustrates a detailed view of body portion 31b and tip
portion 30b of outer sheath 12b of introducer 10b in accordance
with one embodiment of the invention. In particular, FIG. 2F is a
partial side view of outer sheath 12b, FIG. 2G is an end view of
outer sheath 12b, and FIG. 2H is a cross-sectional view taken along
the length of body portion 31b of outer sheath 12b.
Body portion 31b has a substantially oval or oblong cross-section
extending along the length of body portion 31b. Tip portion 30b has
a substantially oval or oblong cross-section that tapers in the
direction from the end adjacent body portion 31b toward tip end
29b. The cross-section of lumen 28b at the tip end 29b of outer
sheath 12b may substantially conform to the exterior cross-section
of body portion 18b of inner penetrator 14b.
In some embodiments, the materials and dimensions of body portion
31b and/or tip portion 30b of outer sheath 12b may be selected to
provide some degree of flexibility to outer sheath 12b such that
outer sheath 12b may flex around particular features in the body,
and such that when introducer 10b is advanced along a guide wire,
outer sheath 12b (along with inner penetrator 14b) may flex to
substantially follow curvatures in the guide wire such that the
guide wire is not significantly displaced by the advancing
introducer 10.
For example, as shown in FIG. 2F, the wall thickness of tip portion
30b, denoted as thickness "T.sub.ost," which may be substantially
uniform around the cross-sectional perimeter of tip portion 30b,
may decrease toward tip end 29b. In some embodiments, the wall
thickness T.sub.ost of tip portion 30b is less than or
approximately equal to 0.03 inches at its thickest point along tip
portion 30b and/or less than 0.02 inches at tip end 29b. In a
particular embodiment, the wall thickness T.sub.ost is between
approximately 0.007 inches and approximately 0.018 inches around
the cross-sectional perimeter at tip end 29b. The decreased wall
thickness, T.sub.ost, of tip portion 30b toward tip end 29b may
provide for increased flexibility of tip portion 30b.
In addition, as shown in FIG. 2F, the perimeter and/or
cross-sectional area of lumen 28b may decrease or taper toward tip
end 29b. In particular, in embodiments in which outer sheath 12b,
including tip portion 30b, has an oval or oblong cross-section
(such as shown in FIGS. 2G and 2H), both the horizontal inner
diameter "ID.sub.osth" and the horizontal outer diameter,
"OD.sub.osth" of tip portion 30b, and both the vertical inner
diameter "ID.sub.stv" and the vertical outer diameter "OD.sub.ostv"
of tip portion 30b may decrease or taper toward tip end 29b. The
terms "horizontal" and "vertical" are used merely for illustrative
purposes of FIGS. 2F-2G, as outer sheath 12b may be positioned in
any orientation.
The tapered outer diameters OD.sub.osth and OD.sub.ostv and reduced
wall thickness, T.sub.ost, at tip end 29b may provide a relatively
smooth transition between tip end 29b and body portion 18b of inner
penetrator 14b (better illustrated in FIG. 2E). Such smooth
transition may reduce or eliminate the likelihood of the juncture
between outer sheath 12b and inner penetrator 14b getting stuck or
caught up, or pushing tissue forward, as introducer 10b is advanced
within the body.
The tapered lumen 28b (e.g., tapered inner diameters ID.sub.osth
and ID.sub.ostv) may provide for a tight or close fit at tip end
29b of outer sheath 12b with the outer surface of body portion 18b
of inner penetrator 14b, such that inner penetrator 14b may be held
substantially in place by outer sheath 12b. In some embodiments,
the tapered lumen 28b provides for an interference fit between
outer sheath 12b and inner penetrator 14b, at least at tip end 29b
of outer sheath 12b.
In addition, the length of tip portion 30b, denoted as length
"L.sub.ost," compared to wall thickness T.sub.ost, inner diameters
ID.sub.osth and ID.sub.ostv and/or outer diameters OD.sub.osth and
OD.sub.ostv, may be selected to provide desired flexibility of tip
portion 30b. For example, the ratio of the length L.sub.ost to wall
thickness T.sub.ost at the thinnest point may be greater than or
approximately equal to 10 to 1. Such configuration and dimensions
may provide desired flexibility for tip portion 30b.
The wall thickness of body portion 31b, denoted as thickness
"T.sub.osm," which remains substantially constant along the length
of body portion 31b, may be less than or approximately equal to
0.03 inches. In a particular embodiment, wall thickness T.sub.osm
is approximately 0.024 inches. Such configuration and dimensions
may provide desired flexibility for middle transition region
37b.
FIGS. 3A-3F illustrate an example method of implanting a paddle
style electrical stimulation lead into a human's epidural space
using an example introducer 10 (such as introducer 10a or
introducer 10b, for example). Spinal cord 47 is also shown. A
location between two vertebrae is selected for the procedure. The
site may be selected using fluoroscopy. The first step in
performing the procedure is to insert needle 41, preferably at an
angle, into the skin, and through the subcutaneous tissue and
ligamentum flavum 44 of the spine, and into a human's epidural
space 40. In one embodiment of the method, for example, the
introducer might be inserted at an angle of approximately
thirty-five to approximately forty-five degrees. FIG. 3A
illustrates insertion of needle 41 through the skin between spinous
processes 42 of two vertebrae 43. Entry into epidural space 40 by
needle 41 may be confirmed using standard methods such as the
"loss-of-resistance" technique after stylet 45, or inner portion of
needle 41, is removed.
After removing stylet 45 from needle 41, guide wire 46 may be
inserted through needle 41 into epidural space 40, shown in FIG.
3B. A guide wire is used in a preferred embodiment of the method of
insertion but is not required to insert a paddle style lead through
the introducer. This part of the procedure may be performed under
fluoroscopic guidance for example. Fluoroscopy may be used to check
the position of guide wire 46 in epidural space 40 before inserting
introducer 10. In some embodiments, a removable stylet may be
inserted into a channel extending within and along the length of
guide wire 46 and manipulated by the operator in order to help
steer guide wire 46 into position. The stylet may also provide
additional rigidity to guide wire 46, which may be desired in
particular applications. Once the tip of guide wire 46 is in
position within epidural space 40, needle 41 is removed. If a
stylet was inserted into guide wire 46 as discussed above, the
stylet may or may not be removed. For example, the stylet may be
left in guide wire 46 in order to increase the rigidity or strength
of guide wire 46 in order to resist guide wire 46 being moved by
the advancement of introducer 10, as discussed below.
As shown in FIG. 3C, introducer 10 may then be inserted, preferably
at an angle of approximately thirty-five to approximately
forty-five degrees, although the exact angle may differ depending
on technique and a patient's anatomy, over guide wire 46 and into
epidural space 40 using guide wire 46 as a guide. The technique of
passing introducer 10 over guide wire 46 helps ensure proper
placement of introducer 10 into epidural space 40 and helps avoid
inadvertent passage of introducer 10 into an unsuitable location.
The operator may choose to cut the skin around the insertion site
with a scalpel to facilitate subsequent entry of introducer 10
through the needle entry site. As discussed above, a stylet within
guide wire 46 may increase the rigidity of guide wire 46 to resist
guide wire 46 being moved or dislocated by introducer 10 as
introducer 10 advances along guide wire 46. In some embodiments, as
introducer 10 advances along flexures in guide wire 46, the tip of
inner penetrator 14 and/or all or portions of outer sheath 12 may
flex to maneuver around obstructions or physical structures in the
body (such as a spinous process 42, vertebrae 43, or any other
structure in the body) and/or to substantially follow curvatures in
guide wire 46, rather than displacing portions of guide wire 46,
which may cause damage to the body. An example of such flexing is
shown and discussed below with reference to FIGS. 7A-7D.
As introducer 10 is passed through the skin it elongates the hole
in the skin made by needle 41. As introducer 10 is passed deeper
into the paravertebral tissues, it spreads the fibers of tissue,
muscle and ligamentum flavum 44 and forms a tract through these
tissues and into epidural space 40, preferably without cutting the
tissues. At the level in the tissues where introducer 10 meets and
penetrates ligamentum flavum 44 there is a second loss of
resistance when inner penetrator 14 has completely penetrated the
ligamentum flavum 44. Shoulder or ridge 23 of outer sheath 12 is
preferably lodged against ligamentum flavum 44 during insertion of
a paddle style lead.
Once introducer 10 has completely penetrated ligamentum flavum,
inner penetrator 14 and guide wire 46 may be removed, leaving outer
sheath 12 positioned in epidural space 40, as shown in FIG. 3D. As
shown in FIG. 3E, paddle style lead 50 may then be inserted through
outer sheath 12 and positioned at an optimal vertebral level, using
fluoroscopy for example, for the desired therapeutic effect. As
shown in FIG. 3F, outer sheath 12 may then be removed leaving only
paddle style lead 50 in epidural space 40, where paddle style lead
50 can be further manipulated if necessary to achieve a desired
therapeutic effect. Paddle style lead 50 may be secured by suturing
it to a spinous process. In some embodiments, a removable stylet
may be inserted into a channel extending within and along the
length of lead 50 and manipulated by the operator in order to help
steer lead 50 into position, such as described in U.S. Publication
No. 2002/0022873, filed on Aug. 10, 2001, for example. The stylet
may also provide additional rigidity to lead 50, which may be
desired in particular applications.
As described above, introducer 10 may be used to implant paddle
style lead 50 into epidural space 40 for spinal nerve stimulation.
The same or an analogous, perhaps smaller, introducer 10 may be
used to implant an analogous paddle style lead 50 into any
appropriate region of the body for peripheral nerve stimulation.
For example, such a paddle style lead 50 may have an outer sheath
12 and lumen 28 with a width of approximately 1 mm to approximately
3 mm.
A similar method of insertion (not expressly shown) may be used to
implant a paddle style electrical stimulation lead into a human's
peripheral nerve tissue. In this embodiment of the invention a site
for insertion in tissue near a nerve is selected. The first step in
performing the procedure is to insert a needle into the skin and
through the subcutaneous tissue and into tissue near a peripheral
nerve. If the needle has a stylet, it may be removed and a guide
wire may be inserted through the needle and into the tissue near a
peripheral nerve. A guide wire may not be required. Fluoroscopy may
or may not be used to guide insertion of a guide wire into tissue
near a peripheral nerve. Once the tip of the guide wire, or needle,
is in the tissue near a peripheral nerve, introducer 10 may be
inserted, preferably at an angle that would depend on the anatomy
of the body near the peripheral nerve to be stimulated. As
introducer 10 is passed through tissues, it elongates the tract
made by a needle or guide wire and spreads the tissue. After
positioning introducer 10 in tissue adjacent to the peripheral
nerve to be stimulated, inner penetrator 14 is removed. A paddle
style lead may then be inserted through outer sheath 12. Outer
sheath 12 may then be removed leaving only the paddle style lead in
position near the peripheral nerve to be stimulated.
Now referring to FIGS. 4A and 4B, there are shown two embodiments
of a stimulation system 200, 300 in accordance with the present
invention. The stimulation systems generate and apply a stimulus to
a tissue or to a certain location of a body. In general terms, the
system 200, 300 includes a stimulation or energy source 210, 310
and a lead 50 for application of the stimulus. The lead 110 shown
in FIGS. 4A and 4B is the paddle style lead 50 of the present
invention.
As shown in FIG. 4A, the stimulation system 200 includes the lead
50 that is coupled to the stimulation source 210. In one
embodiment, the stimulation source 210 includes an implantable
pulse generator (IPG). As is known in the art, an implantable pulse
generator (IPG) is implanted within the body (not shown) that is to
receive electrical stimulation from the stimulation source 210. An
example IPG may be one manufactured by Advanced Neuromodulation
Systems, Inc., such as the Genesis.RTM. System, part numbers 3604,
3608, 3609, and 3644, or the Eon.RTM. System, part numbers 65-3716,
65-3851, and 64-1254.
As shown in FIG. 4B, the stimulation system 300 includes the lead
50 that is coupled to the stimulation source 310. The stimulation
source 310 includes a wireless receiver. As is known in the art,
the stimulation source 310 comprising a wireless receiver is
implanted within the body (not shown) that is to receive electrical
stimulation from the stimulation source 310. An example wireless
receiver 310 may be those wireless receivers manufactured by
Advanced Neuromodulation Systems, Inc., such as the Renew.RTM.
System, part numbers 3408 and 3416.
The wireless receiver (not shown) within stimulation source 310 is
capable of receiving wireless signals from a wireless transmitter
320. The wireless signals are represented in FIG. 4B by wireless
link symbol 330. The wireless transmitter 320 and a controller 340
are located outside of the body that is to receive electrical
stimulation from the stimulation source 310. A user of the
stimulation source 310 may use the controller 340 to provide
control signals for the operation of the stimulation source 310.
The controller 340 provides control signals to the wireless
transmitter 320. The wireless transmitter 320 transmits the control
signals (and power) to the receiver in the stimulation source 310
and the stimulation source 310 uses the control signals to vary the
signal parameters of the electrical signals that are transmitted
through lead 110 to the stimulation site. An example wireless
transmitter 320 may be those transmitters manufactured by Advanced
Neuromodulation Systems, Inc., such as the Renew.RTM. System, part
numbers 3508 and 3516.
As will be appreciated, the connectors are not visible in FIGS. 4A
and 4B because the contact electrodes are situated within a
receptacle (not shown) of the stimulation source 210, 310. The
connectors are in electrical contact with a generator (not shown)
of electrical signals within the stimulation source 210, 310. The
stimulation source 210, 310 generates and sends electrical signals
via the lead 50 to the electrodes 160. Understandably, the
electrodes 160 are located at a stimulation site (not shown) within
the body that is to receive electrical stimulation from the
electrical signals. A stimulation site may be, for example,
adjacent to one or more nerves in the central nervous system (e.g.,
spinal cord) or peripheral nerves. The stimulation source 210, 310
is capable of controlling the electrical signals by varying signal
parameters (e.g., intensity, duration, frequency) in response to
control signals that are provided to the stimulation source 210,
310.
As described above, once lead 110 is inserted into either the
epidural space or near the peripheral nerve, introducer 10 is
removed. Lead 110 extends from the insertion site to the implant
site (the area of placement of the generator). The implant site is
typically a subcutaneous pocket that receives and houses the IPG or
receiver (providing stimulation source 210, 310). The implant site
is usually positioned a distance away from the stimulation site,
such as near the buttocks or other place in the torso area. In most
cases, the implant site (and insertion site) is located in the
lower back area, and lead 110 may extend through the epidural space
(or other space) in the spine to the stimulation site (e.g., middle
or upper back, neck, or brain areas). Once the system is implanted,
the system of leads and/or extensions may be subject to mechanical
forces and movement in response to body movement. FIG. 5
illustrates the steps that may be used to implant a stimulation
system 200, 300 into a human.
FIGS. 6A-6E illustrate an example method of removing an implanted
paddle style electrical stimulation lead 50 from a human's epidural
space 40 using introducer 10b according to one embodiment of the
invention. Such method may be used to remove an electrical
stimulation lead 50 for any suitable reason, such as to relocate,
replace, or repair the lead 50, for example. As discussed below,
the method may be particularly advantageous for removing a lead 50
around which tissue may have grown and is thus firmly secured
within the body. Although the method is discussed with reference to
introducer 10b, the method may be similarly performed using any
suitable introducer, such as introducer 10a, for example.
As shown in FIG. 6A, a paddle style electrical stimulation lead 50
having a body portion 52 and a stimulating portion 54 may be
implanted in a human's epidural space 40 in order to stimulate a
nerve, such as discussed above regarding the method shown in FIGS.
3A-3F, for example. An end 56 of lead 50 extends out of the
epidural space 40 and, in some cases, out through the person's skin
or into a subcutaneous pocket formed during implantation Introducer
10b, including inner penetrator 14b inserted into outer sheath 12b,
may be inserted around body portion 52 of lead 50 such that end 56
of lead 50 runs though inner channel 22b of inner penetrator 14b.
As shown in FIG. 6A, introducer 10b may be advanced such that end
56 of lead 50 protrudes through opening 26b in handle portion 16b
of inner penetrator 14b.
As shown in FIG. 6B, in some embodiments or situations, a stylet
400 may be inserted into a channel that extends along the length of
lead 50, if appropriate. For example, stylet 400 may be a stylet
typically used for guiding lead 50 during the positioning of lead
50 within the body. Stylet 400 may be advanced partially or
completely along the length of lead 50, and may be advanced into
stimulating portion 54 of lead 50. As discussed below, stylet 400
is inserted into lead 50 in order to increase the rigidity of lead
50 such that when the introducer 10b advances along flexures in
body portion 52 of lead 50, tip region 25b of inner penetrator 14b
and/or other portions of introducer 10b may flex to substantially
follow the flexures in body portion 52 of lead 50.
As shown in FIG. 6C, introducer 10b may be advanced along body
portion 52 of lead 50 until tip region 25b of inner penetrator 14b
is adjacent with, or comes into contact with, stimulating portion
54 of lead 50. As it advances, introducer 10b may separate tissue
from body portion 52 of lead 50, such as tissue that may have
formed around body portion 52 over time, thus creating a passageway
through the body. In situations in which body portion 52 extends
out through the skin, the operator may choose to cut the skin
around the entry point of lead 50 with a scalpel to facilitate
subsequent entry of introducer 10. In addition, as introducer 10b
advances along flexures in body portion 52 of lead 50, due at least
in part to the added strength added to lead 50 by stylet 400, tip
region 25b of inner penetrator 14b and/or all or portions of outer
sheath 12b may flex to maneuver around obstructions or physical
structures in the body (such as a spinous process 42, vertebrae 43,
or any other structure in the body) and/or to substantially follow
curvatures in body portion 52 of lead 50, rather than displacing
portions of lead 50, which may cause damage to the body or lead 50.
An example of such flexing is shown and discussed below with
reference to FIGS. 7A-7D. In some embodiments, this part of the
procedure may be performed under fluoroscopic guidance. For
example, fluoroscopy may identify radio-opaque markers 34b and 35b
on inner penetrator 14b and outer sheath 12b, as well as
radio-opaque portions of lead 50, such that the operator (e.g.,
doctor) may determine the relative positions of introducer 10b and
lead 50 during the procedure.
As shown in FIG. 6D, when introducer 10b has been advanced until
inner penetrator 14b is adjacent with or contacting stimulating
portion 54 of lead 50, outer sheath 12b may be advanced forward
(e.g. by sliding) relative to inner penetrator 14b until outer
sheath 12b covers at least a portion of stimulation portion 54 of
lead 50. Outer sheath 12b may be advanced forward until it
completely covers stimulation portion 54 of lead 50. Advancing
outer sheath 12b over stimulation portion 54 may separate tissue
from stimulating portion 54, such as tissue that may have grown
attached to stimulating portion 54. In some embodiments, this part
of the procedure may be performed under fluoroscopic guidance. For
example, fluoroscopy may identify radio-opaque markers 34b and 35b
on inner penetrator 14b and outer sheath 12b, as well as
radio-opaque portions of lead 50, such that the operator (e.g.,
doctor) may determine the relative positions of inner penetrator
14b, outer sheath 12b, and stimulating portion 54 of lead 50 during
the procedure.
As shown in FIG. 6E, inner penetrator 14b, outer sheath 12b, and
lead 50 may all be removed together through the passageway created
by advancing introducer 10b along lead 50, as discussed above
regarding FIG. 6C. In this manner, lead 50 may be removed from the
body without causing significant damage to the body or to the lead
50. As discussed above, the method may be particularly advantageous
for removing a lead 50 around which tissue may have grown and is
thus firmly secured within the body.
FIGS. 7A-7D illustrate example views of introducer 10b flexing as
it moves along a guide wire 46 or stimulation lead 50 within the
body, in accordance with certain embodiments of the invention. In
particular, all or portions of tip portion 25b of inner penetrator
14b may substantially flex to follow bands or curves in guide wire
46 or stimulation lead 50. In some embodiments, due to the relative
shapes and dimensions (e.g., the relative wall thicknesses) of tip
transition region 36b, middle transition region 37b, and body
transition region 38b, tip transition region 36b may be the most
flexible, followed by middle transition region 37b, followed by
body transition region 38b. In addition, in some embodiments, such
as where outer sheath 12b is formed from a polymer, all or portions
of outer sheath 12b may also flex to partially or substantially
follow curvatures in guide wire 46 or stimulation lead 50, such as
shown in FIGS. 7C and 7D, for example.
Such flexibility of inner penetrator 14b and/or outer sheath 12b
may provide several advantages, as discussed above. First, such
flexibility may be advantageous for navigating introducer 10b into
particular regions in the body, such as the epidural region, for
example, which may also reduce the likelihood of introducer 10b
damaging tissue in the body. Also, such flexibility may partially
or substantially prevent introducer 10b from displacing guide wire
46 as introducer 10b moves along guide wire 46 (which displacement
may disrupt the lead insertion or removal process and/or damage
tissue in the body.
FIG. 8 illustrates an example lead introducer kit 500 for preparing
to implant an electrical stimulation lead for electrical
stimulation of nerve tissue in a human, according to one embodiment
of the invention. Generally, lead introducer kit 500 includes a
lead blank 502 and one or more various tools or accessories for
preparing for implanting an actual electrical stimulation lead into
a human body. The lead blank 502 may be used, for example, to
determine whether an actual electrical stimulation lead to be
implanted will fit into the target location in the body. For
example, an electrical stimulation lead may not fit into the
epidural space due to scar tissue or other blockages within the
epidural space. Thus, if it is determined using lead blank 502 that
an electrical stimulation lead will not fit into the target
location in the body, the electrical stimulation lead need not be
removed from its packaging, thus allowing the electrical
stimulation lead to be used on another patient or at a later time.
This may be advantageous due to the relatively high cost of some
electrical stimulation leads.
In the embodiment shown in FIG. 8, lead introducer kit 500 includes
lead blank 502, a needle 504, and a guide wire 506, and a lead
introducer 508. Lead introducer kit 500 may include other tools or
accessories for preparing to implant an electrical stimulation
lead, but in preferred embodiments does not include the actual
electrical stimulation lead. Lead blank 502 may have an identical
or similar shape and size as an electrical stimulation lead to be
inserted into the body for electrical stimulation of nerve tissue.
As discussed above, lead blank 502 may be configured for insertion
into the human body to determine whether the electrical stimulation
lead may be inserted into the desired location proximate the nerve
tissue to be stimulated. For example, lead blank 502 may be
configured for insertion into the human body using the various
methods and/or devices discussed herein, or using any other known
methods and/or devices.
Lead blank 502 may include a removable stylet 510 which may be used
for steering lead blank 502 during insertion and/or positioning of
lead blank 502. Stylet 510 may be inserted into a channel extending
within lead blank 502 and manipulated by an operator in order to
help steer lead blank 502. In addition, in some embodiments, the
shape of lead blank 502 may be configured to facilitate steering of
lead blank 502. For example, lead blank 502 may be a paddle shape
with one or more indentions, notches, or score lines that may
increase the flexibility of lead blank 502. For instance, FIG. 9
illustrates an example lead blank 502 including a paddle style
portion 514 having a scalloped shape. The scalloped shape may
increase the flexibility and steerability of lead blank 502.
Needle 504 may include any needle suitable for inserting guide wire
506 into a desired location in the body, such as a human's epidural
space, for example, such as needle 41 discussed above regarding the
method of FIGS. 3A-3F. Needle 504 may include a removable stylet
516, such as stylet 45 discussed above, for example.
Lead introducer 508 may include any one or more devices for
inserting lead blank 502 into the human body. In some embodiments,
lead introducer 508 may comprise introducer 10 or introducer 10b
described herein, or any other suitable lead introducer. Thus, in
some embodiments, lead introducer 508 may include an outer sheath
530 and an inner penetrator 532. Outer sheath 530 may be inserted
into a human body near nerve tissue to be stimulated. Inner
penetrator 532 may be removably housed within outer sheath 530 and
may include an inner channel configured to receive and be advanced
along guide wire 506 to a desired location relative to the nerve
tissue to be stimulated. Inner penetrator 532 may then be removed
from outer sheath 530, leaving outer sheath 530 substantially in
position for insertion (or attempted insertion) of lead blank 502
through the outer sheath to determine whether an actual electrical
stimulation lead may be properly inserted into position proximate
the nerve tissue to be stimulated. Thus, as discussed above, if
lead blank 502 will not fit into the target location in the body,
it may be determined that the actual electrical stimulation lead
will similarly not fit into the target location. Thus, the
electrical stimulation lead, which may be included in a separate
kit or otherwise packaged separately from lead introducer kit 500,
need not be removed from its packaging, thus avoiding wasting an
electrical stimulation lead, which may be relatively expensive.
FIG. 10 illustrates an example paddle style electrical stimulation
lead 50a having electrodes on only one side, and markings
indicating the directional orientation of the lead 50a, according
to one embodiment of the invention. Paddle style lead 50a may
include any suitable number of electrodes 160a. Electrodes 160a may
be flat electrodes that emit energy out of only of the two sides.
Such electrodes 160a may be desirable for very small paddle leads,
for example. Since the electrodes 160a emit energy out of only one
side, the orientation (i.e., which side is facing in which
direction) of the paddle style lead 50a may be important,
particularly when implanting the lead 50a adjacent the target nerve
tissue.
Thus, lead 50a may include one or more markers 550 that may be
detected by one or more medical imaging techniques (such as
ultrasound, fluoroscopy, MRI, fMRI and/or X-ray, for example) to
indicate the directional orientation of the lead 50a. For example,
lead 50a may include one or more radio-opaque markers 550 having
particular shapes or relative locations such that the operator may
determine the orientation of the lead 50a.
FIG. 11 illustrates an example paddle style electrical stimulation
lead 50b having a substantially uniform paddle-shaped cross-section
extending along the body of the lead 50b, according to one
embodiment of the invention. Paddle style lead 50b includes a body
portion 52b and a stimulating portion 54b, and a number of
electrodes 160b located at stimulating portion 54b. The
cross-section of paddle style stimulating portion 54b, which may
be, for example, a substantially oval, oblong, or rectangular
cross-section, may substantially extend along all or at least a
significant portion of the length of body portion 52b. In some
embodiments, the substantially uniform cross-section may extend at
least to a point outside the epidural region, or outside the skin.
In particular embodiments, the substantially uniform cross-section
may extend all the way back to the stimulation or power source.
This uniform cross-section may make it easier to remove lead 50b
from a human body as compared with leads having a smaller
cross-sectioned lead body. For example, epidural tissue may grow
around an implanted lead body over time. Such tissue may impede the
removal of traditional paddle style leads. The substantially
uniform cross-section of paddle style lead 50b prevents or reduces
the ability of such tissue to impede the removal of implanted lead
50b from the body.
FIG. 12 illustrates an example paddle style electrical stimulation
lead 50c having a tear away body portion, according to one
embodiment of the invention. Paddle style lead 50c may be similar
to paddle style lead 50b shown in FIG. 11. In particular, paddle
style lead 50c may includes a body portion 52c, a stimulating
portion 54c, a number of electrodes 160c located at stimulating
portion 54c, and a substantially uniform cross-section (such as a
substantially oval, oblong, or rectangular cross-section, for
example) extending back along body portion 52c. Body portion 52c
may include a tear-away portion 560 that may be torn away or
otherwise removed, revealing a small cross-sectioned lead body
(such as a standard lead body wire or cord, for example) that may
extend back to the stimulation or power source. Tear-away portion
560 is indicated by perforated tear lines 562. However, tear-away
portion 560 may have any other configuration and may be removed in
any other suitable manner. In some embodiments, such as shown in
FIG. 12, the distance from stimulating portion 54c to tear-away
portion 560 may be selected or designed such that when lead 50c is
implanted in the body, the forward edge of tear-away portion 560
may be located near or just outside the epidural region 562, or the
skin. Thus, lead 50c may provide the advantage of being relatively
easy to remove from the body (due to the substantially uniform
cross-section, as discussed above), as well as providing a smaller,
more manageable body portion 54c leading back to the stimulation or
power source.
Although the present invention has been described with several
embodiments, a number of changes, substitutions, variations,
alterations, and modifications may be suggested to one skilled in
the art, and it is intended that the invention encompass all such
changes, substitutions, variations, alterations, and modifications
as fall within the spirit and scope of the appended claims.
* * * * *